Foam cushion for headphones

ABSTRACT

A composite foam cushion for a sound control device. The cushion includes a core formed of a polymeric foam material and a polymeric coating overlying at least a portion of the core of polymeric foam material. The polymeric coating includes an outer coating layer and an inner polymeric coating layer bonded to the core of polymeric foam material. The inner coating layer may provide the cushion with strength, while providing a high degree of flexibility and suppleness to closely conform around contours and obstructions. The outer coating layer may provide the cushion with enhanced abrasion resistance and/or chemical resistance while having an aesthetically pleasing feel and appearance.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation application of U.S. patentapplication Ser. No. 14/628,468, filed Feb. 23, 2015 which is acontinuation of U.S. patent application Ser. No. 14/290,476, filed May29, 2014, now U.S. Pat. No. 8,960,366 which is a continuation of U.S.patent application Ser. No. 13/646,405, filed Oct. 5, 2012, now U.S.Pat. No. 8,746,397, which claims priority to U.S. ProvisionalApplication No. 61/545,009, filed Oct. 7, 2011, the entire disclosuresof which are incorporated herein by reference.

TECHNICAL FIELD

The disclosure is directed to foam pads or cushions for use inheadphones and other sound control devices. More particularly, thedisclosure is directed to foam pads or cushions having enhancedsuppleness while maintaining high abrasion resistance and durability.

BACKGROUND

A conventional cushioned headphone device includes a pair of cushionsconfigured to press against a user's head and at least partiallysurround the outer ears of the user. In addition to isolating the user'sears from outside sounds, such cushions are intended to at leastpartially conform around irregularities of the head and outer ear of theuser, as well an any intervening structures (e.g., eyeglass frames).However, known cushions lack the level of conformability to closelyfollow the contours of a user's anatomy while retaining sufficientdurability to withstand continued use.

Accordingly, it is desirable to provide alternative configurations offoam cushions for headphones and earmuffs that are configured to closelyconform to the user's anatomy which have an aesthetically pleasing feeland appearance, yet sufficient durability to withstand continued use.

SUMMARY

The disclosure is directed to several alternative designs, materials andmethods of manufacturing foam pads or cushions for headphones, earmuffs,and other sound controlling devices.

Accordingly, one illustrative embodiment is a composite foam cushion fora sound control device. The composite foam cushion includes a coreformed of a polymeric foam material and a polymeric coating overlying atleast a portion of the core of polymeric foam material.

The polymeric coating may include an inner polymeric coating layerpositioned outward of the core of polymeric foam material and an outerpolymeric coating layer positioned outward of the inner polymericcoating layer. The inner polymeric coating layer may be bonded to thepolymeric foam material of the core, and the outer polymeric coatinglayer may be bonded to the inner polymeric coating layer.

The composite foam cushion may have a Conformability Gap Value of 0.650inches or less, 0.635 inches or less, 0.625 inches or less, 0.615 orless, or 0.600 inches or less.

The composite foam cushion may have an average Indentation Force Ratioof 0.090 or less, 0.085 or less, 0.080 or less, or 0.075 or less over aProtrusion Value range of 2.0 to 7.0 millimeters.

The core of polymeric foam material may have a first glass transitiontemperature at about −45° C. and a second glass transition temperatureat about −25° to −30° C. or about −20° to −30° C.

Another illustrative embodiment is a composite foam cushion for a soundcontrol device to be placed against the head or ear of a user. Thecomposite foam cushion includes a core formed of a polymeric foammaterial and a polymeric coating overlying at least a portion of thecore of polymeric foam material. The polymeric coating includes an innerpolymeric coating layer positioned around at least a portion of the coreof polymeric foam material and an outer polymeric coating layer disposedover at least a portion of the inner polymeric coating layer. The innerpolymeric coating layer is formed of a polymeric composition including acrosslinker, and the outer polymeric coating layer is formed of apolymeric composition including a crosslinker. The inner polymericcoating layer is less crosslinked than the outer coating layer.

The crosslinker of the polymeric composition of the outer polymericcoating layer may be present in a greater weight percent than thecrosslinker of the polymeric composition of the inner polymeric coatinglayer and/or the crosslinker of the polymeric composition of the outerpolymeric coating layer may be different than the crosslinker of thepolymeric composition of the inner polymeric coating layer.

Another illustrative embodiment is a composite foam cushion for a soundcontrol device. The composite foam cushion includes a polymeric foamcore formed of a foaming reaction of an isocyanate with a polyetherpolyol in the presence of a catalyst. The composite foam cushion alsoincludes an inner polymeric coating layer and an outer polyurethanebased polymeric coating layer chemically bonded to the inner polymericcoating layer. The outer polyurethane based polymeric coating layer isformed of a mixture of a polyurethane dispersion, a coalescing media, awetting agent, and a crosslinker. The inner polymeric coating layer isless crosslinked than the outer polymeric coating layer.

Another illustrative embodiment is a sound control device for placementon the head of a user. The sound control device includes a pair of earpieces with a band extending between the ear pieces. Each ear pieceincludes a composite foam cushion as described herein. The sound controldevice may include transducers or drivers fitted in the ear pieces totransmit sound into the ear canal of a user.

The core of polymeric foam material of the composite foam cushion may bea molded core formed in a molding process, and the polymeric coating ofthe composite foam cushion may be molded over the molded core during themolding process.

The molded polymeric coating may include an inner polymeric coatinglayer positioned outward of the annular core of polymeric foam materialand an outer polymeric coating layer positioned outward of the innerpolymeric coating layer.

Yet another illustrative embodiment is a method of forming a cushion fora sound control device. The method includes applying an outer polymericcoating layer into a cavity of a mold and applying an inner polymericcoating layer into the cavity of the mold over the outer polymericcoating layer. A polymeric foam composition is disposed into the cavityof the mold after applying the inner and outer polymeric coating layersinto the cavity of the mold. The polymeric foam composition is thenfoamed in the cavity. The polymeric foam composition, the outerpolymeric coating layer, and the inner polymeric coating layer are thencured in the cavity of the mold.

Each of the outer polymeric coating layer and the inner polymericcoating layer may be allowed to dry prior to disposing the polymericfoam composition into the cavity of the mold.

The mold may be heated to an elevated temperature of 50° C. or morebefore applying the outer polymeric coating layer into the cavity of themold.

The polymeric foam composition may be controllably metered into thecavity of the mold such that when the foam composition foams, thequantity of foam composition disposed into the cavity forms a foam corehaving a volume substantially filling the cavity without appreciablyexceeding the volume of the cavity.

The polymeric foam composition may diffuse into the inner polymericcoating layer and/or into the outer polymeric coating layer during themolding process.

The above summary of some example embodiments is not intended todescribe each disclosed embodiment or every implementation of theaspects of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The aspects of the disclosure may be more completely understood inconsideration of the following detailed description of variousembodiments in connection with the accompanying drawings, in which:

FIG. 1A is a perspective view of an exemplary sound control device,illustrated as a set of headphones, incorporating a cushion as describedherein;

FIG. 1B is a front view of an exemplary sound control device,illustrated as a pair of ear caps, incorporating a cushion as describedherein;

FIG. 2 is a cross-sectional view of an exemplary cushion as describedherein;

FIG. 3 is an enlarged cross-section of a portion of a cushion asdescribed herein;

FIG. 4 is a perspective view of an exemplary testing apparatus for usein the Indentation Test as described herein;

FIG. 5 is a perspective view of the testing fixture of the testingapparatus of FIG. 4 for use in the Indentation Test as described herein;

FIG. 6 is a side cross-sectional view of the testing fixture initiallycontacting a cushion in accordance with the Indentation Test asdescribed herein;

FIG. 7 is a side cross-sectional view of the testing fixture pressedinto a cushion a specified amount in accordance with the IndentationTest as described herein;

FIG. 8 illustrates the results of the Indentation Test for a samplecushion made in accordance with this disclosure;

FIG. 9 illustrates the results of the Indentation Test for a cushionfrom a pair of Bose AE2 headphones;

FIG. 10 illustrates the results of the Indentation Test for a cushionfrom a pair of 3M Peltor headphones;

FIG. 11 is a perspective view of an exemplary testing apparatus for usein the Pressure Point Test as described herein;

FIG. 12 is a cross-sectional view of a portion of the testing apparatusfor use in the Pressure Point Test as described herein;

FIG. 13 is a cross-sectional view of a cushion being subjected to thePressure Point Test as described herein; and

FIG. 14 is a graph illustrating acquired results from cushion samplessubjected to the Pressure Point Test.

While the aspects of the disclosure are amenable to variousmodifications and alternative forms, specifics thereof have been shownby way of example in the drawings and will be described in detail. Itshould be understood, however, that the intention is not to limitaspects of the disclosure to the particular embodiments described. Onthe contrary, the intention is to cover all modifications, equivalents,and alternatives falling within the spirit and scope of the disclosure.

DETAILED DESCRIPTION

For the following defined terms, these definitions shall be applied,unless a different definition is given in the claims or elsewhere inthis specification.

All numeric values are herein assumed to be modified by the term“about”, whether or not explicitly indicated. The term “about” generallyrefers to a range of numbers that one of skill in the art would considerequivalent to the recited value (i.e., having the same function orresult). In many instances, the term “about” may be indicative asincluding numbers that are rounded to the nearest significant figure.

The recitation of numerical ranges by endpoints includes all numberswithin that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4,and 5).

Although some suitable dimensions, ranges and/or values pertaining tovarious components, features and/or specifications are disclosed, one ofskill in the art, incited by the present disclosure, would understanddesired dimensions, ranges and/or values may deviate from thoseexpressly disclosed.

As used in this specification and the appended claims, the singularforms “a”, “an”, and “the” include plural referents unless the contentclearly dictates otherwise. As used in this specification and theappended claims, the term “or” is generally employed in its senseincluding “and/or” unless the content clearly dictates otherwise.

The following detailed description should be read with reference to thedrawings in which similar elements in different drawings are numberedthe same. The detailed description and the drawings, which are notnecessarily to scale, depict illustrative embodiments and are notintended to limit the scope of the disclosure. The illustrativeembodiments depicted are intended only as exemplary. Selected featuresof any illustrative embodiment may be incorporated into an additionalembodiment unless clearly stated to the contrary.

FIG. 1A illustrates an exemplary sound control device, in the form ofheadphones, headsets or earmuffs 10 utilizing foam pads or cushions 20for secure yet comfortable placement over and/or on the ears of a user.In some instances, the sound control device 10 may be of theover-the-ear type (i.e., circumaural) configured to surround orencompass the ears of the user, or of the on-ear type (i.e.,supra-aural) configured to sit on the top of the ears of the user. Thesound control device 10 may include a pair of ear pieces including apair of cups 12, 14 for placement over or on the ears of a user, and aheadband or strap 16 extending between and connecting the opposing earunits 12, 14 of the headphones or earmuffs 10. The strap 16 may providea resilient force to urge the ear pieces (e.g., the cushions 20 of theear pieces) into contact with the head and/or ears of the user to helpretain the headphones or earmuffs 10 on the user's head. The strap 16may be curved to conform around a portion of the user's head and/oradjustable in length to accommodate different sized heads. The cushions20 may be secured directly or indirectly to a perimeter of the cups 12,14 by any desired means, including mechanical fasteners or devices,adhesive compositions, or other fastening mechanisms. In instances inwhich the sound control device 10 is a set of headphones, a cord 18 mayextend from one or both of the ear pieces to provide an electricalpathway for transmitting an audio signal to transducers or driversfitted in the ear pieces, or the transducers or drivers in the earpieces of the headphones may wirelessly receive an audio signal.

FIG. 1B illustrates an alternative sound control device 10′, in the formof ear caps, utilizing foam pads or cushions 20′ for secure yetcomfortable placement in the ear of a user. The sound control device 10′may include a pair of ear pieces including cushions 20′ configured torest in the concha of a user's ear to cover the ear canal, and aheadband or strap 16′ extending between and connecting the opposing earpieces. The strap 16′ may provide a resilient force to urge the earpieces (e.g., the cushions 20′ of the ear pieces) into contact with earsof the user to cover the user's ear canals. The strap 16′ may be curvedto conform around a portion of the user's head and/or adjustable inlength to accommodate different sized heads. The cushions 20′ may besecured directly or indirectly to the strap 16′ by any desired means,including mechanical fasteners or devices, adhesive compositions, orother fastening mechanisms.

The cushions 20 may provide a sealing layer between the cups 12, 14 ofthe headphones, headset or earmuffs 10 and the head of the usersurrounding the user's ears, sealing off unwanted sound from enteringthe user's ear canal and reaching the user's ear drum. For example, thecushions 20, which may be annular members, may include a layer of soundattenuating polymeric foam material 50 at an interface between acircumferential rim of the cups 14, 16 and the head of the user toprevent unwanted sounds from reaching the user's ear drums. The cushions20 may be sufficiently supple to comfortably fit against the user's headwhile substantially conforming to the contours of the user's head andany intervening structure (e.g., eyeglass frames, etc.). Furthermore,the cushions 20 may be sufficiently durable and chemical resistant toinsure the integrity of the cushions 20 is maintained throughout theuseful life of the cushions 20.

Furthermore, in some instances, a polymeric composite foam cushion 20 asdescribed herein, may be provided on the headband or strap 16 of a soundcontrol device 10 to provide an interface between the sound controldevice and top of the user's head, for example, to improve the comfortlevel of the sound control device 10 on the user's head.

As mentioned above, in some instances the cushion 20 may be an annularmember configured to at least partially surround the outer ear of auser. In other instances, the cushion 20 may be a disc shape, orotherwise shaped body configured to be pressed against the ear. In onesuch configuration, the cushion 20 may include one or more, or aplurality of openings allowing sound to pass through the cushion 20 orbe provided with a porous sound transmission portion, for example. Insome instances, the cushion 20 may be a thin layer attached to anintervening cushion or pad, or other structure, of a sound controldevice, such that the cushion 20 is arranged to provide an interfacebetween the sound control device and the user's anatomy. A cross-sectionof an exemplary composite cushion 20 is shown in FIG. 2. As can be seen,the composite foam cushion 20 may include a polymeric coating or filmoverlying at least a portion of a polymeric foam core 50. For example,the polymeric coating or film may be disposed over and substantiallysurround the polymeric foam core 50. In at least some instances, thepolymeric coating or film may include an outer coating or film layer 30and an inner coating or film layer 40 disposed between the outer coatinglayer 40 and the polymeric foam core 50. It is noted that forillustrative purposes the thickness of the outer and inner coatinglayers 30, 40 is greatly exaggerated in FIG. 2.

The core 50, which may be a body of foam material, may be resilientlycompressible against the head or ear of a user. For example, thepolymeric foam core 50 may be formed of an open cell foam materialhaving a desired porosity. In some instances, the polymeric foam formingthe core 50 may have an open cell structure, a closed cell structure ora combination of open and closed cells. In some instances, the polymericfoam material forming the core 50 may be a slow recovery foam, having arecovery time in the range of 1 second to 60 seconds measured at 37degrees Celsius and 50% relative humidity. In some embodiments, thepolymeric foam core 50 may be formed of a polyurethane foam materialhaving an open-cell structure. In other embodiments, the polymeric foamcore 50 may be formed of another foam material, such as polyvinylchloride (PVC), for example, a plasticized polyvinyl chloride foam.Although some suitable materials have been identified, other suitablepolymers may be found useful for forming the core 50.

The inner polymeric coating layer 40 may surround or cover at least aportion of the inner polymeric foam core 50. For example, the innerpolymeric coating layer 40 may be juxtaposed with the polymeric foamcore 50 and thus provide an interface 45 between the inner polymericcoating layer 40 and the polymeric foam core 50. The inner polymericcoating layer 40 may be bonded (e.g., chemically bonded, mechanicallybonded, adhesively bonded) to the polymeric foam core 50 throughout theinterface 45 between the inner polymeric coating layer 40 and thepolymeric foam core 50 as shown in FIG. 3. In some instances, a chemicalbond between the inner polymeric coating layer 40 and the polymeric foamcore 50 may be formed during the molding process for forming the cushion20, as described further herein.

The outer polymeric coating layer 30 may surround or cover at least aportion of the inner polymeric coating layer 40. For example, the outerpolymeric coating layer 30 may be juxtaposed with the inner polymericcoating layer 40, and thus provide an interface 35 between the outerpolymeric coating layer 30 and the inner polymeric coating layer 40. Theouter polymeric coating layer 30 may be bonded (e.g., chemically bonded,mechanically bonded, adhesively bonded) to the inner polymeric coatinglayer 40 throughout the interface 35 between the inner polymeric coatinglayer 40 and the outer polymeric coating layer 30. In some instances, achemical bond between the inner polymeric coating layer 40 and the outerpolymeric coating layer 30 may be formed during the molding process forforming the cushion 20, as described further herein.

In some instances, as a result of the molding process for forming thecushion 20, diffusion of the polymeric foam material of the core 50 intothe inner coating layer 40, or diffusion of the polymeric foam materialof the core 50 into the inner and outer coating layers 40, 30, mayoccur. For example, polymeric foam material forming the core 50 maydiffuse across the interface 45 and into the inner polymeric coatinglayer 40 in some instances. In other instances, polymeric foam materialforming the core 50 may diffuse into the outer polymeric coating layer30 across the interface 35, as well as across the interface 45 and intothe inner polymeric coating layer 40.

In some instances, the mold in which the cushion 20 is molded mayinclude a textured cavity which may form a corresponding textured outersurface 25 on the cushion 20. Thus, the outer surface 25 of the outercoating layer 30 may have a visually identifiable texture thereonimparted by the mold. The visually discernable texture may providepreferential creasing and/or dissipation of wrinkling when the cushion20 is subjected to compression and deformation, as well as providing thecushion 20 with an aesthetically pleasing feel and appearance.

Outer Coating Layer

The outer coating layer 30 may be present to provide the cushion 20 withenhanced abrasion resistance and/or chemical resistance while having anaesthetically pleasing feel and appearance. The outer coating layer 30may be a polymeric coating formed of a desired mixture of constituentsto provide the desired characteristics for the outer coating layer 30.In some embodiments, the outer coating layer 30 may be an unfoamedpolymeric coating distinct from the inner coating layer 40 and the core50. For example, the outer coating layer 30 may be a urethane based(e.g., polyurethane) polymeric coating, a vinyl based (e.g., polyvinylchloride) polymeric coating, or an acrylic based polymeric coating. Insome embodiments, the outer coating layer 30 may be formed from amixture of polyurethane dispersions (or polyvinyl chloride dispersionsif vinyl based), coalescing solvents, wetting agents, and/orcrosslinkers. The outer coating layer 30 may be an aqueous basedcoating, a solvent based coating, or a solvent-less based coating (e.g.,UV cured coating), for example.

Some suitable polyurethane dispersions include: Hauthane HD 4670 and/orHauthane HD 2024, each available from Hauthaway Corporation, of Lynn,Mass., or NeoRez R-1010, available from DSM NeoResins of Wilmington,Mass. The Hauthane HD 4670 dispersion provides a very soft, flexibleurethane coating layer. The Hauthane HD 4670 dispersion may be selecteddue to its resulting coating layer having a very low elastic modulus andhigh elongation at break. The Hauthane HD 4670 resulting coating has anelastic modulus of 200 psi at 100% elongation, with an elongate at breakof 800%. The Hauthane HD 2024 dispersion provides a soft, tough, andflexible urethane coating having very good abrasion resistance, and maybe selected due to its low elastic modulus while still containing goodtensile strength and elongation. The Hauthane HD 2024 dispersionprovides a coating with an elastic modulus of 480 psi at 100%elongation, 680 psi at 200% elongation and 890 psi at 300% elongation,with an ultimate tensile strength of 4,000 psi and elongation at breakof 750%. In addition to providing high tensile strength, the inclusionof Hauthane HD 2024 dispersion may reduce the tackiness and increasechemical resistance of the coating layer. The NeoRez R-1010 polyurethanedispersion may provide a soft feel effect, excellent chemicalresistance, and low gloss. The NeoRez R-1010 dispersion may be selectedto improve the feel of the coating layer and decrease the gloss level ofthe coating layer. The outer coating layer 30 may have an elasticmodulus of about 500 psi or less, about 400 psi or less, about 300 psior less, about 250 psi or less, about 200 psi or less, or about 150 psior less at 100% elongation, for example. The outer coating layer 30 mayhave an elongation at break of 600% or more, 650% or more, 700% or more,750% or more, or 800% or more, for example.

Dipropylene n-butyl ether (DPnB) is one suitable coalescing medium.Alternative coalescing media which may alternatively or additionally beused include dipropylene glycol methyl ether (DPM) or propylene glycolmethyl ether, as well as other media known to those skilled in the art.

Suitable wetting agents include silicone and non-silicone basedchemistries, such as the silicone based wetting agent BYK 348 availablefrom BYK Chemie of Wallingford, Conn. Alternatively or additionally,other silicone surfactants may also be included in the coating mixture,if desired. One suitable non-silicone based wetting agent isAerosol-OT-75 available from Cytec of West Patterson, N.J.

Suitable crosslinkers may include polymeric carbodiimide basedcrosslinkers, such as V-02-L2 and E2 available from Nisshinbo/GSI-EximAmerica of New York, N.Y. Carbodilite V-02-L2, or a similar crosslinker,may be selected to increase the chemical resistance and strength of thecoating layer, without significantly hardening the coating layer.

The mixture for the outer coating layer 30 may also include additionaladditives including a defoamer (e.g., a silicone based defoamer or anon-silicone based defoamer) or anti-foaming agent, such as BYK 028available from BYK Chemie of Wallingford, Conn. Furthermore, the mixturefor the outer coating layer 30 may include a pigment to provide theouter coating layer 30 with a desired coloration. For example, themixture for the outer coating layer 30 may include a black pigment, forexample a carbon black aqueous pigment dispersion, such as UCD 1507Qavailable from Plasticolors Inc. of Ashtabula, Ohio. However, otherpigments may be included, if desired. Other additives include UVstabilizers, antioxidants, fillers, and anti-microbials, for example.

In forming the polymeric mixture for the outer coating layer 30, thepolymeric dispersion(s) may be provided in the range of 70 to 80 weightpercent of the total formulation, the coalescing media(s) may beprovided in the range of 0 to 10 weight percent of the totalformulation, the wetting agent(s) may be provided in the range of 0.05to 0.7 weight percent of the total formulation, and the crosslinker(s)may be provided in the range of 5 to 11 weight percent of the totalformulation, or about 5 to 8 weight percent of the total formulation,based on solids of polyurethane present.

One suitable formulation of the outer coating layer 30 is as follows:

Formulation 1 Ingredient (Weight %) HD 2024¹ 16.37 HD 4670² 61.36R-1010³ 4.09 DPnB⁴ 1.10 Water 1.21 V-02-L2⁵ 6.90 BYK 348⁶ 0.70 BYK 028⁷0.09 UCD 1507Q⁸ 8.19 ¹Hauthane HD-2024 - Hauthaway Corp., Lynn MA²Hauthane HD-4670 - Hauthaway Corp., Lynn MA ³NeoRez R-1010 - DSMNeoResins, Wilmington, MA ⁴dipropylene n-butyl ether (DPnB) - DowCorning Corp., Midland, MI ⁵V-02-L2 - Nisshinbo/GSI-Exim America, NewYork, NY ⁶BYK 348 - BYK Chemie, Wallingford, CT ⁷BYK 028 - BYK Chemie,Wallingford, CT ⁸UCD 1507Q - Plasticolors Inc., Ashtabula, OH

In the formulation above, the Hauthane HD 4670 polyurethane dispersionmay be provided in the range of 40-80 weight percent, the HauthaneHD2024 polyurethane dispersion may be provided in the range of 0-70weight percent, and the NeoRez R-1010 polyurethane dispersion may beprovided in the range of 0-50 weight percent of the total formulation.

The thickness of the outer coating layer 30 may be in the range of about0.5 mils to about 3.0 mils (0.0005 inches to 0.003 inches), about 0.5mils to about 2.5 mils (0.0005 inches to 0.0025 inches), about 0.5 milsto about 2.0 mils (0.0005 inches to 0.002 inches), or about 0.5 mils toabout 1.5 mils (0.0005 inches to 0.0015 inches) in some instances.

Inner Coating Layer

The inner coating layer 40 may be present to provide the cushion 20 withstrength, while providing a high degree of flexibility and suppleness toclosely conform around contours and obstructions. The inner coatinglayer 40 may be a polymeric coating formed of a desired mixture ofconstituents to provide the desired characteristics for the innercoating layer 40. In some embodiments, the inner coating layer 40 may bean unfoamed polymeric coating distinct from the outer coating layer 30and the core 50. For example, the inner coating layer 40 may be aurethane based (e.g., polyurethane) polymeric coating, a vinyl based(e.g., polyvinyl chloride) polymeric coating, or an acrylic basedpolymeric coating. In other embodiments, the inner coating layer 40 maybe a nitrile based coating, such as a high acrylonitrile based nitrilerubber coating or a medium acrylonitrile based nitrile rubber coating.In some instances a high acrylonitrile based nitrile rubber coating maybe selected due, at least in part, to its chemical and moistureresistance and high mechanical strength. In some embodiments, the innercoating layer 40 may be formed of a mixture of polyurethane dispersions(or polyvinyl chloride dispersions if vinyl based), coalescing solvents,wetting agents, and/or crosslinkers. The inner coating layer 40 may bean aqueous based coating, a solvent based coating, or a solvent-lessbased coating (e.g., UV cured coating), for example.

One suitable high acrylonitrile based nitrile rubber coating is based onthe 1571X12 Nychem™ emulsion available from Emerald PerformanceMaterials, of Akron, Ohio. This emulsion shows high chemical andmoisture resistance as well as high mechanical strength.

Some suitable polyurethane dispersions include: Hauthane HD 4670 and/orHauthane HD 2024, each available from Hauthaway Corporation, of Lynn,Mass. The Hauthane HD 4670 dispersion provides a very soft, flexibleurethane coating layer. The Hauthane HD 4670 dispersion may be selecteddue to its very low elastic modulus and elongation at break. TheHauthane HD 4670 resulting coating has an elastic modulus of 200 psi at100% elongation, with an elongate at break of 800%. The Hauthane HD 2024dispersion provides a soft, tough, and flexible urethane coating havingvery good abrasion resistance, and may be selected due to its lowelastic modulus while still containing good tensile strength andelongation. The Hauthane HD 2024 dispersion provides a coating with anelastic modulus of 480 psi at 100% elongation, 680 psi at 200%elongation and 890 psi at 300% elongation, with an ultimate tensilestrength of 4,000 psi and elongation at break of 750%. In addition toproviding high tensile strength, the inclusion of Hauthane HD 2024dispersion may reduce the tackiness and increase chemical resistance ofthe coating layer. The inner coating layer 40 may have an elasticmodulus of about 400 psi or less, about 300 psi or less, about 250 psior less, or about 200 psi or less at 100% elongation, for example. Theinner coating layer 40 may have an elongation at break of 500% or more,600% or more, 700% or more, 750% or more, or 800% or more, for example.

The inner coating layer 40 may also include an aromatic polyurethanedispersion (PUD) to increase the bonding between the foam core 50 andthe polymeric coating. For example, the inner coating layer 40 mayinclude a blend, such as a 50:50 blend based on total weight percent ofthe dispersions in the formulation, of an aromatic polyurethanedispersion and the Hauthane HD 4670 dispersion. One suitable aromaticpolyurethane dispersion is PU-444 available from Picassian Polymers, ofPeabody Mass. PU-444 exhibits excellent adhesion to a wide variety ofsubstrates. The polymer chains of the PU-444 aromatic polyurethanedispersion break down when exposed to light, thus the outer coatinglayer 30 may shield the PU-444 in the inner coating layer 40 from lightto prevent breakdown of the polymer chains.

Dipropylene n-butyl ether (DPnB) is one suitable coalescing medium.Alternative coalescing media which may alternatively or additionally beused include dipropylene glycol methyl ether (DPM) or propylene glycolmethyl ether, as well as other media known to those skilled in the art.

Suitable wetting agents include silicone and non-silicone basedchemistries, such as the silicone based wetting agent BYK 348 availablefrom BYK Chemie of Wallingford, Conn. Alternatively or additionally,other silicone surfactants may also be included in the coating mixture,if desired. One suitable non-silicone based wetting agent isAerosol-OT-75 available from Cytec of West Patterson, N.J.

Suitable crosslinkers may include polymeric carboniimide basedcrosslinkers, such as V-02-L2 and E2 available from Nisshinbo/GSI-EximAmerica of New York, N.Y. Carbodilite E2, or a similar crosslinker, maybe selected to increase the chemical resistance and strength of thecoating layer, while reducing the tacky nature of the coating layer atelevated temperatures. The mixture for the inner coating layer 40 mayalso include additional additives including a defoamer (e.g., a siliconebased defoamer or a non-silicone based defoamer) or anti-foaming agent,such as BYK 028 available from BYK Chemie of Wallingford, Conn.Furthermore, the mixture for the inner coating layer 40 may include apigment to provide the inner coating layer 40 with a desired coloration.For example, the mixture for the inner coating layer 40 may include ablack pigment, for example a carbon black aqueous pigment dispersion,such as UCD 1507Q available from Plasticolors Inc. of Ashtabula, Ohio.However, other pigments may be included, if desired.

In forming the polymeric mixture for the inner coating layer 40, thepolymeric dispersion(s) may be provided in the range of 80 to 98 weightpercent of the total formulation, the coalescing solvent(s) may beprovided in the range of 0 to 10 weight percent of the totalformulation, the wetting agent(s) may be provided in the range of 0.05to 0.8 weight percent of the total formulation, and the crosslinker(s)may be provided in the range of 0 to 7 weight percent of the totalformulation, or about 3 to 4 weight percent of the total formulation,based on solids of polyurethane present.

One suitable formulation of the inner coating layer 40 is as follows:

Formulation 1 Ingredient (Weight %) HD 4670¹ 89.27 DPnB² 1.18 Water 1.29E2³ 2.95 BYK 348⁴ 0.76 BYK 028⁵ 0.10 UCD 1507Q⁶ 4.46 ¹Hauthane HE-4670 -Hauthaway Corp., Lynn MA ²dipropylene n-butyl ether (DPnB) - Dow CorningCorp., Midland, MI ³E2 - Nisshinbo/GSI-Exim America, New York, NY ⁴BYK348 - BYK Chemie, Wallingford, CT ⁵BYK 028 - BYK Chemie, Wallingford, CT⁶UCD 1507Q - Plasticolors, Ashtabula, OH

In the formulation above, the Hauthane HD 4670 polyurethane dispersionmay be provided in the range of 50-98 weight percent, and in someinstances 0-50 weight percent of the Hauthane HD2024 polyurethanedispersion may be added to the total formulation.

Another suitable formulation of the inner coating layer 40 is asfollows:

Formulation 2 Ingredient (Weight %) 1571X12¹ 99 Synperonic 13/6² 0.4Aerosol OT75³ 0.4 Chartwell B 515.71W⁴ 0.2 ¹Nychem ™ 1571X12 - EmeraldPerformance Materials, Akron, OH ²Synperonic 13/6 - Croda, Edison, NJ³Aerosol OT75 - Cytec, West Patterson, NJ ⁴Chartwell B 515.71W -Chartwell International, Inc., North Attleborough, MA

The thickness of the inner coating layer 40 may be in the range of about0.5 mils to about 3.0 mils (0.0005 inches to 0.003 inches), about 0.5mils to about 2.5 mils (0.0005 inches to 0.0025 inches), about 0.5 milsto about 2.0 mils (0.0005 inches to 0.002 inches), or about 0.5 mils toabout 1.5 mils (0.0005 inches to 0.0015 inches) in some instances.

The compositions for the inner polymeric coating layer 40 and the outerpolymeric coating layer 30 may be chosen such that the inner polymericcoating layer 40 is less crosslinked than the outer coating layer 30.Although less crosslinked than the outer coating layer 30, the innerpolymeric coating layer 40 may have a chemical composition similar tothe chemical composition of the outer polymeric coating layer 30.Accordingly, the inner polymeric coating layer 40 may include adifferent crosslinker and/or a smaller quantity (e.g., weight percent)of a crosslinker than the outer polymeric coating layer 30 to providethe varied crosslinking between the outer and inner coating layers 30,40. Furthermore, the outer polymeric coating layer 30 and the innerpolymer coating layer 40 may each include functional groups that causethe layers to adhere together, whether by chemical or mechanical bondsor forces.

Moreover, the inner polymeric coating layer 40 may be chemicallycompatible with the outer polymeric coating layer 30. For instance, theinner polymeric coating layer 40 and the outer polymeric coating layer30 may both be formed of polymeric materials of a chemically similarfamily of polymers (e.g., urethanes, vinyls). In some instances, theinner polymeric coating layer 40 and the outer polymeric coating layer30 may both be polyurethane based polymers. For example, the outerpolymeric coating layer 30 may be formed of a mixture of two or morepolyurethane dispersions, while the inner polymeric coating layer 40 maybe formed of at least one of the polyurethane dispersions of the outerpolymeric coating layer 30. In some instances, the polyurethanedispersion included in both the outer polymeric coating layer 30 and theinner polymeric coating layer 40 may be provided in a greater weightpercent in the inner polymeric coating layer 40 than in the outerpolymeric coating layer 30. In other instances, the inner polymericcoating layer 40 may be an acrylonitrile based nitrile rubber, such as ahigh acrylonitrile based nitrile rubber coating or a mediumacrylonitrile based nitrile rubber coating, and the outer polymericcoating layer 30 may be formed of a polyurethane dispersion or a mixtureof two or more polyurethane dispersions.

Foam Core

The polymeric foam material forming the core 50 may be formed in variousmanners. For instance, the polymeric foam material forming the core 50may be formed by combining an isocyanate with a polyol, blowing agent,and catalyst mixture to react and form a polyurethane foam or combininga reactive system of another polymeric mixture with a blowing agent toform a polymeric foam material. In other instances, the polymeric foammaterial forming the core 50 may be a vinyl based (e.g., polyvinylchloride) polymeric foam material.

Although other compositions are contemplated, in some instances thepolymeric foam material may be an open cell polyurethane foam made byreacting an isocyanate, such as the Suprasec 2527 prepolymer supplied byHuntsman Corporation of Salt Lake City, Utah, with a polyol mixture,such as a mixture of one or more of polyols listed below, in thepresence of a catalyst, such as Niax A-1 available from MomentivePerformance Materials of Columbus, Ohio, Dabco BL-11 available from AirProducts of Allentown, Pa., and/or Dabco 33-LV available from AirProducts of Allentown, Pa. Niax A-1 contains 70%bis(2-dimethylaminoethyl) ether. Dabco 33-LV is a solution of 33%triethylenediamine and 67% dipropylene glycol.

The polyol mixture may include one or more polyether polyols, such asglycerine and propylene oxide based polyether polyol triols, and/or oneor more bio-based polyols. Some suitable polyether polyols include:Carpol GP-240, a 700 molecular weight glycerine and propylene oxidebased polyether polyol triol, available from Carpenter Company ofRichmond, Va.; Carpol GP-3008, a 3000 molecular weight glycerine andpropylene oxide based polyether polyol triol with 8% ethylene oxidelocated internally, available from Carpenter Company of Richmond, Va.;Carpol GP-6515, a 6000 molecular weight glycerine and propylene oxidebased polyether polyol triol with 15% ethylene oxide located internally,available from Carpenter Company of Richmond, Va.; Carpol GP-5171, areactive 5000 molecular weight glycerine and propylene oxide basedpolyether polyol triol with 71% ethylene oxide capacity, available fromCarpenter Company of Richmond, Va.; BiOH 5400, a bio-based polyol foruse in polyurethanes having a molecular weight of 1445, available fromCargill, Inc. of Minneapolis, Minn.; and Duranol™ T5652, a polycarbonatediol, available from Asahi Kasei Chemicals Corp. of Tokyo, Japan.

The composition of the polymeric foam material forming the core 50 mayalso include one or more surfactants (e.g., wetting agents, foamstabilizing agents, etc.) or other additives. For example, thecomposition may include a foam stabilizing agent, such as Dabco DC-198available from Air Products of Allentown, Pa. and/or Dabco DC-5982 alsoavailable from Air Products of Allentown, Pa.; a stabilizing additive,such as Geolite Modifier 210 available from Momentive PerformanceMaterials of Columbus, Ohio to produce foam at a lower index; and/or anadditive to strengthen and improve the tensile/elongation/tearproperties of the foam, such as Niax DP-1022 available from MomentivePerformance Materials of Columbus, Ohio.

In some instances, a filler material, such as a short acrylic fiberfiller may be incorporated into the foam to provide added strength,toughness and/or abrasive resistance.

In some instances, a gel, such as a polyurethane gel, could beincorporated into the foam to provide more uniform pressure and improvedheat capacity of the foam. The gel may be added to the foam as a feedstream into the mix head for the polymeric foam composition, or added inanother way, if desired.

Some suitable formulations of the polymeric foam composition forming thecore 50 are as follows:

Formula- Formula- Formula- Formula- Formula- tion 1 tion 2 tion 3 tion 4tion 5 (Weight (Weight (Weight (Weight (Weight Ingredient %) %) %) %) %)GP-240¹ 29.76 — 31.44 — — GP-3008² 12.89 7.71 3.51 — — GP-6515³ — — — —0.22 GP-5171⁴ 18.6 31.84 26.57 29.04 28.48 BiOH — 23.26 — 38.11 37.385400⁵ T5652⁶ — — — — 4.45 Niax — 1.29 — 0.95 0.93 DP1022⁷ Geolite 5.535.55 4.65 4.24 4.16 210⁸ Dabco DC- 0.25 0.75 0.75 0.68 0.45 198⁹ DabcoDC- — 0.5 — 0.45 0.45 5982¹⁰ Dabco 33- 0.37 0.37 0.37 0.34 0.33 LV¹¹Niax A-1¹² 0.12 0.12 0.12 0.11 0.11 Suprasec 32.48 28.61 32.59 26.0823.04 2527¹³ ¹Carpol GP-240 - Carpenter Company, Richmond, VA ²CarpolGP-3008 - Carpenter Company, Richmond, VA ³Carpol GP-6515 - CarpenterCompany, Richmond, VA ⁴Carpol GP-5171 - Carpenter Company, Richmond, VA⁵BiOH 5400 - Cargill Inc., Minneapolis, MN ⁶Duranol T5652 - Asahi KaseiChemicals Corp., Tokyo, Japan ⁷Niax DP-1022 - Momentive PerformanceMaterials, Columbus, OH ⁸Geolite Modifier 210 - Momentive PerformanceMaterials, Columbus, OH ⁹Dabco DC-198 - Air Products, Allentown, PA¹⁰Dabco DC-5982 - Air Products, Allentown, PA ¹¹Dabco 33-LV - AirProducts, Allentown, PA ¹²Niax A-1 - Momentive Performance Materials,Columbus, OH ¹³Suprasec 2527 - Huntsman Corporation, Salt Lake City, UT

The follow table provides some suitable ranges for ingredients of apolymeric foam material which may be used to form the core 50 withsatisfactory resulting properties.

Formulation Ingredient (Weight %) GP-5171³ 23.1-31.8 BiOH 5400⁴28.8-40.9 Niax DP1022⁵ 0.4-1.3 Geolite 210⁶ 4.15-5.5  Dabco DC-198⁷0.25-0.75 Dabco DC-5982⁸   0-0.5 Dabco 33-LV⁹ 0.34-0.37 Niax A-1¹⁰0.11-0.12 Suprasec 2527¹¹ 23.0-32.6

It is noted that with the above provided ranges of ingredients of a foammaterial formulation, the ratio of equivalent weight of GP-5171 to theequivalent weight of BiOH 5400 be in the range of 0.13 to 0.30.

The polymeric foam material forming the foam core 50 may be a slowrecovery, viscoelastic foam, having a softness uncharacteristic of otherslow recovery, viscoelastic foams, which are stiffer. Typically, theglass transition temperature, Tg, of viscoelastic foams is about 0° C.However, the polymeric foam material for the foam core 50 describedherein at Formulation 4 has a first Tg at about −45° C. and a second Tgat about −25° to −30° C. or about −20° to −30° C. The lower glasstransition temperatures of the foams formed in accordance with thisdisclosure allow the foams to feel softer and retain that softness to alower operating temperature compared to other foams having equaldensities. In some instances, the polymeric foam core 50 may have afirst glass transition temperature of less than 0° C. and a second glasstransition temperature of about −25° or less. In some instances, thepolymeric foam core 50 may have a first glass transition temperature ofless than −10° C. and a second glass transition temperature of about−25° or less, a first glass transition temperature of less than −20° C.and a second glass transition temperature of about −25° or less, a firstglass transition temperature of less than −30° C. and a second glasstransition temperature of about −25° or less, or a first glasstransition temperature of less than −40° C. and a second glasstransition temperature of about −25° or less or about −20° or less.

Manufacturing Process

The cushion 20 may be formed according to the following process. A moldmay be provided having a cavity therein shaped in the desired shape ofthe cushion 20. In some instances the surface of the mold defining thecavity may be a textured surface having a desired texture for impartingon the outer surface of the cushion 20. The mold may be formed ofsilicone, metal, polymer or other material as desired. The mold mayinitially be heated to an elevated temperature in the range of about 20°C. to about 90° C., in the range of about 50° C. to about 90° C., orabout 70° C., for example. While at the elevated temperature, the outercoating layer 30 may be applied to the surface of the cavity of the moldin liquid form and then allowed to dry. In some instances, the outercoating layer 30 may be sprayed, poured, painted or otherwise appliedinto the mold. In some instances, the outer coating layer 30 may dryalmost instantaneously as the elevated temperature of the mold tends toevaporate the solvent (e.g., water) in the outer coating layer 30,although the outer coating layer 30 may not yet be fully cured at thisstage.

Thereafter, the inner coating layer 40 may be applied in a liquid formon the previously applied outer coating layer 30 in the cavity of themold. In some instances, the inner coating layer 40 may be sprayed,poured, painted, or otherwise applied into the mold over the outercoating layer 30. The inner coating layer 40 may then be allowed to dry,which in some instances may occur almost instantaneously at the elevatedtemperature of the mold, as the solvent (e.g. water) in the innercoating layer 40 evaporates. Similar to the outer coating layer 30, theinner coating layer 40 may not yet be fully cured at this stage.

With the outer and inner coating layers 30, 40 applied to the mold andallowed to dry, the foam composition is then poured in the cavity of themold and the cavity is capped with a mounting plate which may be bondedto the inner coating layer 40. In some instances, the mounting plate maybe secured with an adhesive. The mold may be vented to atmosphericpressure during the foaming process. The foam composition undergoes afoaming chemical reaction to form a polymeric foam core 50 filling thevolume of the cavity in the mold. In some instances, the foamcomposition may be controllably metered into the mold cavity such thatwhen the foam composition foams, the quantity of foam composition pouredinto the cavity forms a foam core 50 having a volume substantiallyfilling the cavity without appreciably exceeding the volume of thecavity. In some instances, the foaming reaction may be momentarilydelayed (e.g., for about 30 seconds), for example by the inclusion of ablocking acid in the foam composition, to facilitate metering the foamcomposition into the mold. One suitable blocking agent is Dabco BA100,available from Air Products of Allentown, Pa.

The mold and foamed core (with inner and outer coating layers appliedthereto) may then be placed in an oven and heated to an elevatedtemperature of about 70° C. to about 85° C., or up to 120° C. in someinstances, for a duration of time, such as for about 10 to 60 minutes,to allow the foamed core 50, as well as the outer and inner coatinglayers 30, 40, to cure. Thereafter, the mold may be removed from theoven and allowed to cool, prior to removing the formed cushion 20 (i.e.,the foamed core, and inner and outer coating layers) from the cavity ofthe mold. The formed foam pad or core 50, with the outer and innercoating layers 30, 40 bonded thereto, may be removed from the mold, andin instances in which the surface of the cavity is textured, the outercoating layer 30 may have a visually identifiable texture thereonimparted by the mold. The visually discernable texture may providepreferential creasing and/or dissipation of wrinkling when the cushion20 is subjected to compression and deformation, as well as providing thecushion 20 with an aesthetically pleasing feel and appearance.

Indentation Test

In order to quantitatively evaluate the conforming characteristics of acushion as described herein to commercially available competitiveheadphone cushions, a testing apparatus and associated testing methodwere created in house at Hearing Components, Inc. of Oakdale, Minn., theassignee of the current application. The associated test will be calledthe Indentation Test, herein. The object of the Indentation Test is toindirectly measure the gap of the cushion created when a bar is pressedinto the cushion to a specified depth. This test is intended to simulatethe ability of the cushion to conform when engaging the bow of awearer's eyeglasses. The test is conducted in a controlled environmentat ambient temperature (21° C.) and 40% relative humidity.

As shown in FIG. 4, the testing apparatus 100 includes a height gaugestand 102 and a test fixture 110 attached to the arm 104 of the heightgauge stand 102, such as with a mounting bracket 106. The height gaugestand 102 also includes a gauge 108, or other readout, for indexing themeasured height from the height gauge stand 102.

The test fixture 110 is further illustrated in FIG. 5. The test fixture110 includes a plate 112, such as a clear tempered glass purchased fromMcMaster, having a flat, planar lower surface 114. An elongate bar 116is mounted to the plate 112 and extends from the lower surface 114 ofthe plate 112. The bar 116 has a flat, planar lower surface 118,parallel to the lower surface 114 of the plate 112, and two parallelside surfaces 120, 122, extending perpendicular to both the lowersurface 114 of the plate 112 and the lower surface 118 of the bar 116.The bar 116 has a length L sufficient to extend across a cushion (i.e.,3 inches), a height H of 0.125 inches measured between the lower surface114 of the plate 112 and the lower surface 118 of the bar 116, and awidth W of 0.195 inches measured between the parallel side surfaces 120,122.

The test fixture 110 is mounted to the height gauge stand 102 and thelower surface 114 of the plate 112 and the lower surface 118 of the bar116 are coated with talc powder, or other visually discernablesubstance. The talc powder can be applied to the lower surfaces 114, 118with a small sponge, or other applicator. The test cushion C is thenplaced on a rigid, flat surface (e.g., a table top, or bench) below thetest fixture 110, with the lower surface 114 of the plate 112 and thelower surface 118 of the bar 116 facing the cushion C. The test fixture110 is then lowered toward the cushion C until the lower surface 118 ofthe bar 116 first initiates contact with the cushion C, as shown in FIG.6. At the point where the lower surface 118 of the bar 116 initiallycontacts the cushion C, the gauge 108 of the height gauge stand 102 iszeroed out. With the gauge 108 zeroed out, the test fixture 110 islowered 0.375 inches onto the cushion C, as shown in FIG. 7. As the testfixture 110 is lowered onto the cushion C, the bar 116 is pushed intothe cushion C to deform the cushion C around the bar 116 and the lowersurface 114 of the plate 112 is pressed against the upper surface of thecushion C. As shown in FIG. 7, when the cushion C is deformed around thebar 116, a gap X is created where the cushion C is held away from thelower surface 114 of the plate 112. The gap X is the distance betweenthe points 130, 132 on either side of the bar 116 where the cushion Cdeviates from the lower surface 114 of the plate 112 to deflect aroundthe protruding bar 116. The test fixture 110 is held at this position(lowered 0.375 inches from initial contact of the bar 116 with thecushion C) for 5 seconds, and then the test fixture 110 is lifted offthe cushion C. The cushion C is removed from the base and the gap Xbetween the deviation points 130, 132 is visually retained on thecushion C due to the talc powder transferred to the cushion C from thelower surface 114 of the plate 112. The gap X between the deviationpoints 130, 132 (other than the portion in contact with the lowersurface 118 of the bar 116) is not coated with the talc powder, and thusis visually discernable. This gap X is measured, for example, with acalipers. The measured value is documented with the identifyingdescription (e.g., product name, lot number, etc.) of the tested cushionC, and then the test may be repeated for other test cushions C. As usedherein the measured gap X is referred to as the Conformability Gap Valueof the cushion C.

Below, and at FIGS. 8-10, are test results for a sample cushion made atHearing Components, Inc. according to this disclosure, compared to twocompetitor's premium cushions.

Conformability Gap Value Cushion (inches) Hearing Components 0.5940 BoseAE2 0.6715 3M Peltor 0.7770

FIG. 8 shows the gap X and measured value of a sample cushion made atHearing Components, Inc. having a polymeric foam core made from theformulation 4, above, and the formulations of the inner and outercoating layers, provided above. As can be seen from FIG. 8, the gap X ofthe sample cushion had a measured value of 0.5940 inches. FIG. 9 showsthe gap X and measured value of a cushion of Bose AE2 headphones,available from Bose Corporation. The cushion of the Bose AE2 headphonesis a die cut open cell slow recovery foam core encased in a syntheticleather casing. As can be seen from FIG. 9, the gap X of the Bose AE2cushion had a measured value of 0.6715 inches. FIG. 10 shows the gap Xand measured value of a cushion of 3M Peltor headphones, available from3M Corporation. The cushion of the 3M Peltor headphones is an open cellfoam core covered in a vinyl cover. As can be seen from FIG. 10, the gapX of the 3M Peltor cushion had a measured value of 0.7770 inches.

Accordingly, a cushion formed in accordance with this disclosure mayhave a Conformability Gap Value, according to the Indentation Testspecified above, of 0.650 inches or less, 0.635 inches or less, 0.625inches or less, 0.615 or less, or 0.600 inches or less.

The degree of elasticity and compatibility of the elasticities of thelayers of the polymeric coating with the polymeric foam core of theHearing Components cushion contribute to reduce the Conformability GapValue, and thus allow the cushion to more closely conform around anobject, such as the bar of the test fixture. Thus, the HearingComponents cushion is more effective at sealing the ear canal fromunwanted sounds.

Pressure Point Test

In order to quantitatively evaluate the improved comfort provided by thesofter feel of a cushion as described herein to commercially availablecompetitive headphone cushions, a testing apparatus and associatedtesting method were created in house at Hearing Components, Inc. ofOakdale, Minn., the assignee of the current application. The associatedtest will be called the Pressure Point Test, herein. The object of thePressure Point Test is to measure the force on a “high point”—a point onthe user's head or ear that stands at a higher elevation than thesurrounding anatomy. This test is intended to simulate the force exertedon the “high point” of the user's anatomy, and thus the associatedcomfort experienced by the user when the cushion is pressed against the“high point”. The test is conducted in a controlled environment atambient temperature (21° C.) and 37% relative humidity.

As shown in FIG. 11, the testing apparatus 200 includes a Dillon loadcell 202 mounted to a mounting apparatus 204, with a 6.4 millimeterdiameter “button” 206 attached to the end of the Dillion load cell 202(a Dillon model #AFG 100N load cell was used to acquire the resultsprovided herewith). The button 206 has a flat upper surface. The button206 and Dillon load cell 202 are mounted to the mounting apparatus 204such that the button 206 extends through a 9.5 millimeter diameter hole208 in a flat plate 210 of the mounting apparatus 204. The height H ofthe portion of the button 206 protruding above the upper surface of theflat plate 210, as shown in FIG. 12, is adjustable by means of slottedholes in the mounting apparatus 204 used to mount the Dillon load cell202 to the mounting apparatus 204 with threaded fasteners.

The test is carried out by placing a headphone cushion C on the uppersurface of the plate 210 so that the button 206 is aligned with thecross-sectional centerline of the cushion C. In other words, the cushionC is placed above the button 206 such that the central axis of thebutton 206 passes through the center of the cushion C. As shown in FIG.13, a 310 gram weight 212 is then placed on top of the cushion C, andcentered over the button 206. This amount of 310 grams was chosen asthis corresponds to the pressure measured to be exerted on the head byeach side of the commercially available Bose AE2 headphones. The button206 is then progressively set at different heights H (i.e., the distancemeasured between the upper surface of the flat plate 210 and the uppersurface of the button 206) protruding above the flat plate 210, and themeasured value of the force F exerted between the button 206 and thecushion C at each height H is determined with the Dillon load cell 202.As used herein the measured force F is referred to as the IndentationForce Value of the cushion C and the associated height H of the button206 above the plate 210 is referred to as the Protrusion Value. TheIndentation Force Ratio is the ratio of the Indentation Force Value(Newtons) to the Protrusion Value (millimeters).

Below, and in the corresponding graph at FIG. 14 are the test resultsfor a sample cushion made at Hearing Components, Inc. according to thisdisclosure having a polymeric foam core made from the formulation 4,above, and the formulations of the inner and outer coating layers,provided above, compared to a commercially available cushion of Bose AE2headphones.

Indentation Protrusion Force Value Indentation Force Value (Newtons)Ratio (millimeters) HC Sample Bose AE2 HC Sample Bose AE2 2.0 0.16 0.200.080 0.10 3.0 0.22 0.34 0.073 0.11 4.0 0.26 0.40 0.065 0.10 5.0 0.320.48 0.064 0.10 6.0 0.44 0.72 0.073 0.12 7.0 0.52 0.82 0.074 0.12

The data above demonstrates that a cushion formed in accordance withthis disclosure exerted an average of 33% less force on the “high point”than the Bose AE2 cushion. Accordingly, a cushion formed in accordancewith this disclosure may have an Indentation Force Ratio, according tothe Indentation Test specified above, of 0.095 or less, 0.090 or less,0.085 or less, 0.080 or less, 0.075 or less, or 0.070 or less forProtrusion Values of 2.0 to 7.0 millimeters, 2.0 to 6.0 millimeters, 2.0to 5.0 millimeters, 3.0 to 7.0 millimeters, 3.0 to 6.0 millimeters, 3.0to 5.0 millimeters, 4.0 to 7.0 millimeters, 4.0 to 6.0 millimeters, orother ranges of Protrusion Values between 2.0 to 7.0 millimeters. Theaverage Indentation Force Ratio of the HC Sample over the ProtrusionValue range of 2.0 to 7.0 millimeters was 0.072 [(0.52−0.16)/(7.0−2.0)],whereas the average Indentation Force Ratio of the Bose AE2 sample overthe Protrusion Value range of 2.0 to 7.0 millimeters was 0.12[0.82−0.20)/(7.0−2.0)]. In some instances, the composite cushion formedin accordance with this disclosure may have an average Indentation ForceRatio of 0.10 or less, 0.095 or less, 0.090 or less, 0.085 or less,0.080 or less, 0.075 or less, or 0.070 or less over a Protrusion Valuerange of 2.0 to 7.0 millimeters.

The degree of conformability of the Hearing Components cushioncontribute to help distribute forces exerted on a user's head by thecushion, and thus allow the cushion to more comfortably conform to theuser's anatomy and provide a softer feel against the user's head.

Those skilled in the art will recognize that aspects of the presentdisclosure may be manifested in a variety of forms other than thespecific embodiments described and contemplated herein. Accordingly,departure in form and detail may be made without departing from thescope and spirit of the present disclosure as described in the appendedclaims.

What is claimed is:
 1. A composite foam cushion for a sound controldevice to be placed against the head or ear of a user, the compositefoam cushion comprising: a core formed of a polymeric foam material; anda polymeric film overlaying a surface of the core of polymeric foammaterial, the polymeric film including: an inner layer facing thesurface of the core of polymeric foam material, the inner layer isformed of a polymeric composition including a crosslinker; and an outerlayer disposed over the inner layer, the outer layer is formed of apolymeric composition including a crosslinker; wherein the inner layerof the film is less crosslinked than the outer layer of the film.
 2. Thecomposite foam cushion of claim 1, wherein the polymeric composition ofthe inner layer of the film is chemically compatible with the polymericcomposition of the outer layer of the film.
 3. The composite foamcushion of claim 2, wherein the polymeric composition of the inner layerof the film and the polymeric composition of the outer layer of the filmare both polyurethane based polymers.
 4. The composite foam cushion ofclaim 1, wherein the crosslinker of the polymeric composition of theouter layer of the film is different than the crosslinker of thepolymeric composition of the inner layer of the film.
 5. The compositefoam cushion of claim 1, wherein the polymeric composition of the innerpolymeric coating layer is a high acrylonitrile based nitrile rubber andthe polymeric composition of the outer polymeric coating layer is apolyurethane based polymer.
 6. The composite foam cushion of claim 1,wherein the core of polymeric foam material has a first glass transitiontemperature of about −40° C. or less.
 7. The composite foam cushion ofclaim 6, wherein the core of polymeric foam material has a second glasstransition temperature of about −20° C. or less.
 8. The composite foamcushion of claim 1, wherein the crosslinker of the polymeric compositionof the outer layer of the film is present in a greater weight percentthan the crosslinker of the polymeric composition of the inner layer ofthe film.
 9. The composite foam cushion of claim 1, wherein the film isbonded to the surface of the core of polymeric foam material.
 10. Thecomposite foam cushion of claim 1, wherein the crosslinker of the outerlayer of the film is a carbodiimide based crosslinker.
 11. The compositefoam cushion of claim 10, wherein the crosslinker of the inner layer ofthe film is a carbodiimide based crosslinker.
 12. The composite foamcushion of claim 1, wherein the crosslinker of the inner layer of thefilm is a carbodiimide based crosslinker.
 13. A composite foam cushionfor a sound control device, comprising: a core formed of a polymericfoam material; and a polymeric film overlaying a surface of the core ofpolymeric foam material; wherein the composite foam cushion has aConformability Gap Value of 0.650 inches or less.
 14. The composite foamcushion of claim 13, wherein the polymeric film includes an inner layerfacing the surface of the core of polymeric foam material and an outerlayer positioned outward of the inner layer.
 15. The composite foamcushion of claim 14, wherein: the inner layer is formed of a polymericcomposition including a crosslinker; the outer layer is formed of apolymeric composition including a crosslinker; and the inner layer ofthe film is less crosslinked than the outer layer of the film.
 16. Thecomposite foam cushion of claim 15, wherein the polymeric composition ofthe inner layer of the film and the polymeric composition of the outerlayer of the film are both polyurethane based polymers.
 17. Thecomposite foam cushion of claim 15, wherein the crosslinker of thepolymeric composition of the outer layer of the film is different thanthe crosslinker of the polymeric composition of the inner layer of thefilm.
 18. A composite foam cushion for a sound control device,comprising: a core formed of a polymeric foam material; and a polymericfilm overlying a surface of the core of polymeric foam material; whereinthe composite foam cushion has an average Indentation Force Ratio of0.090 or less over a Protrusion Value range of 2.0 to 7.0 millimeters.19. The composite foam cushion of claim 18, wherein the polymeric filmincludes an inner layer facing the surface of the core of polymeric foammaterial and an outer layer positioned outward of the inner layer. 20.The composite foam cushion of claim 19, wherein: the inner layer isformed of a polymeric composition including a crosslinker; the outerlayer is formed of a polymeric composition including a crosslinker; andthe inner layer of the film is less crosslinked than the outer layer ofthe film.